Handel’s Tamerlano has become a calling card for Il Pomo d’Oro, the fine Italian period ensemble founded in 2012. Their recording of this most difficult of the composer’s operas, released last year, was a great achievement, which, along with a series of striking Wigmore Hall concerts, put them very much on the map as far as UK audiences are concerned. Their Barbican debut performance of the piece, part of their current European tour, revealed, however, that something has unfortunately slipped in the interim.

A change of conductor hasn’t helped. In place of the dynamic RiccardoMinasi, we now have the young Russian Maxim Emelyanychev, graceful, almost balletic in his movements, and fascinating to watch. But he seems to think in the moment rather than in terms of dramatic span, and an awkward lack of cumulative momentum undermined the impact of a work that trawls, with insidious slowness, through the mind of a psychopath, chronicling the disastrous consequences of the games he plays with the lives of others. Some sluggish recitatives, and lengthy pauses to retune, further impeded the flow.

The singing was variable, too. Julia Lezhneva’s Asteria, a newcomer to the cast, was unaccountably plagued by intonation and diction problems. John Mark Ainsley, as Tamerlano’s principal victim Bajazet, has been on better form, and his death scene didn’t quite move as it should. There were significant pluses, however. Xavier Sabata’s Tamerlano remains one of the finest Handel operatic performances, outstandingly sung, waspishly characterised and dangerously attractive: you fully understand why his cast off fiancee, Irene (Romina Basso, oddly uncertain in her second aria, but wonderfully authoritative elsewhere), should still be in thrall to him. And Max Emanuel Cencic sang with glorious beauty of tone as Andronico: this is such a great voice. A hit and miss evening, with remarkable moments, but sadly lacking cogency overall.